Two in three busty women are being hugely let down - by stores giving them the wrong bras.

Women with a DD chest or bigger were sent to 70 fittings by consumer campaigners Which?

Yet many of the volunteers, aged 25 to 75, were sold vastly differentsized bras at different shops, the watchdogs reveal today.

One was measured as 34FF at one outlet and elsewhere as 40D, seven sizes larger. Another was deemed a 34C and 34F by two House of Fraser branches - both wrong. Jenny Driscoll, of Which?, said: "The results were shocking. One bra was so poorly fitted there was room for a pair of socks in the cups. If stores are going to offer this service they need to up their game. Do it properly or don't do it at all."

Which? said some women would have been better off "picking something off a market stall".

Fewer than one in three fittings was correct while one in four was so awful its researchers marked it a zero. None of the six tested stores was deemed good enough to recommend. Best of the bunch was John Lewis, with a 45% rating, and Bravissimo, with 43%.

House of Fraser picked up the booby prize on 28%. The other chains in the study were Marks & Spencer, Debenhams and La Senza.

A bad fit can cause aches in the neck, shoulder and back and lead to poor posture and appearance.

Lecturer David Morris, who helped to oversee the tests, said: "A larger bust will generally need a firmer fit, more supportive back elastic and a more reinforced fabric."